JOHANNESBURG/LONDON, Aug 26 (Reuters) - Glencore
, the world's largest commodities trader, stood on
the verge of its largest takeover bid since its May stock market
listing on Friday, after South Africa's Optimum Coal
confirmed it had received approaches.

The move on Optimum, South Africa's sixth-largest coal
producer, illustrates Glencore's appetite for deals in the
volatile equity and commodity markets, which it has said will
throw up bargains.

Sources close to the deal said late on Thursday that the
Swiss-based trader plans to bid for a majority stake in Optimum
with its South African partner, politician-turned-businessman
Cyril Ramaphosa.

Shares in Optimum, worth around $1 billion at current market
prices, were up 5 percent at 31.5 rand at 1223 GMT after hitting
their highest level in about four months.

Glencore, run by South African former coal buyer Ivan
Glasenberg, is already a major player in both the South African
and global coal trades. Its move to grow by snapping up Optimum
taps into what analysts have long said is a need for small and
medium-sized coal miners there to consolidate.

Optimum, a mid-size producer has export capacity and
reserves that make it attractive prey for Glencore and other big
foreign companies hoping to capitalise on Indian and Chinese
demand. South Africa's enviable geographic position, with access
to both the Atlantic and the Pacific coal markets, adds to its
appeal.

Optimum, South Africa's fourth-largest exporter, said on
Friday it had received "unsolicited, non-binding expressions of
interest from third parties to acquire a controlling interest,"
without naming the parties involved.

Glencore declined to comment.

A purchase of the South African company would be Glencore's
most significant since its record listing, when it sacrificed
its fiercely protected privacy to gain the balance sheet
firepower for acquisitions. In the past two months it has made a
$475 million bid for a majority stake in the owner of the Mina
Justa copper project in Peru and has also offered to buy out
minority shareholders in Australian nickel producer Minara.

Optimum earlier this month alerted investors to
circumstances that could affect its share price, but at the time
denied having been approached by any prospective buyers.

"The stock was below 23 rand in early August so you would
see why there is lots of interest at those levels," said Sasha
Naryshkine, an analyst with Vestact in Johannesburg.

"It will depend now on what kind of a premium they are
willing to pay."

GLENCORE CIRCLES

The sources told Reuters on Thursday that Glencore and
Ramaphosa were talking to Optimum shareholders and were
preparing to make an announcement.

Shareholders in Optimum -- including Mandla Tshabalala of
Mobu Resources, a small investor -- confirmed they had received
an offer from the commodities giant and Ramaphosa, whose
unlisted Shanduka Resources owns 30 percent of Shanduka Coal, a
venture with Glencore.

Shanduka Coal has until recently been Glencore's vehicle
for investment in coal mining in South Africa, where it has been
a vital facilitator through prefinancing for some of the smaller
miners.

Glencore's deep pockets and Ramaphosa's influence would make
for a formidable bid which could nullify any opposition arising
from unions or shareholders, some of whom may be reluctant to
see the trader extend its reach in South Africa.

South African coal is famed for its reliable quality and the
speedy handling of exports at the Richards Bay Coal Terminal
have also made it an attractive market.

Coal miners in general, and in Africa in particular, have
suffered from a lack of big ticket investment in mines and in
infrastructure that has created bottlenecks, supporting prices.

Optimum, formerly owned by miner BHP Billiton , will
produce 13.7 million tonnes in 2011, almost flat on 2010.
(Additional reporting by Helen Nyambura in Johannesburg and
Jacqueline Cowhig in London; Editing by Erica Billingham)